An automatic rapid-attachment chuck device for attaching axially insertable chucks to machine chuck heads in bell-forming machines for thermoplastic pipes

Abstract: An automatic rapid-attachment chuck device for attaching axially insertable chucks (1) to machine chuck heads (2) in bell-forming machines for thermoplastic pipes, wherein the chucks (1) are removably and projectingly constrained to a fixed support (6) in the machine chuck heads (2), which support (6) is provided with a flange (4) for centring the chuck (1), said flange (4) having through holes (5) for connecting the chuck (1) to the chuck head (2). The device comprises: a plate (7) affording slots (8) of varying breadth and rotatable on a fixed support (6) on activation of means (11) for actuating and mobile inrelation to the flange (4); pins (9), provided with heads (10), said heads (10) being conformed such as to be able to transit freely through the holes (5) in the flange (4) and through the slots (8) in the plate in a chuck (1) mounting position on the chuck head (2); interefering geometrically with all of the slots( 8) in a second extreme position in which the plate (7) is rotated in relation to the first extreme position, such as to resist a detachment of the chuck (1) from the chuck head.

Description: The invention relates to an automatic rapid-attachment chuck device for attaching axially insertable chucks to machine chuckheads in bell-forming machines for thermoplastic pipes. The chucks are removably and projectingly constrained to a fixed support in the machine chuckheads, which support is provided with a flange for connecting the chuck, said flange being provided with through holes for connecting the chuck to the chuckhead (see e.g. GB-A- 432 528). Bell-forming machines of the above type are equipped with a series of interchangeable chucks, variously shaped, which are combined with heating elements to shape ends of pipes (also of various dimensions) into different geometrical conformations. In such machines the chucks are connected to the flange by a series of conventional bolts which insert into special holes made in the flange itself, so that the chuck is removable and interchangeable in relation to various operations. The fundamental drawback of this connection system is that the substitution of the chucks requires bolt loosening and tightening operations which slow down production. Further, in order to achieve an equal tightening of all the bolts, torque wrenches are necessary as is a logical tightening order of the bolts. The aim of the present invention, as it is characterized in the following claims, is thus to eliminate the above-mentioned drawbacks. The invention solves the problem by providing an automatic chuck rapid-connection device comprising the features of the preamble of claim 1, which further comprises: a plate affording at least two circumferential keyhole slots of varying breadth and being at least rotatingly constrained to a fixed support such as to be rotatably mobile in relation to the flange; at least two pins, provided with heads fixed to the chuck facing towards the flange and with the heads of the pins arranged projectingly, said heads being conformed such as to be able to transit freely through the holes in the flange and through the slots in the plate in a chuck mounting position on the chuck head wherein the plate is arranged in a first extreme rotation position with respect to the flange; said heads interfering geometrically with all of the slots in a second extreme position in which the plate is rotated in relation to the first extreme position, such as to resist a detachment of the chuck from the chuck head of the machine; means for actuating the rotation of the plate between the first and the second extreme positions. The fundamental advantage obtained with the present invention consists in the fact that with a single movement of the plate the chuck is connected (or disconnected) to the chuck head of the machine contemporaneously at all of the pins and all of the plate slots. This leads to drastically reduced mounting times, independently of the number of connection points between the chuck and the flange. This renders production much more economical, and leads to the machine's being more easily adapted to different production needs. Further, the conformation of the locking device, as well as the possibility of automating the actuating means moving the plates contributes to obtaining an identical lock of the chuck at all of its points of connection with the flange, without having to use special equipment and with great operative simplicity for the operator responsible for the machine, who only has to command the activation of the device. Further characteristics and advantages of an embodiment of the present invention will better emerge from the detailed description that follows, of an embodiment of the invention, illustrated in the form of a non-limiting example in the accompanying drawings, in which: figure 1 is a total view of a device according to the invention applied to a chuckhead of a forming machine, sectioned at the axis of symmetry of the chuck; figure 2 is a total view of the device of figure 1, sectioned according to line II-II of figure 1; figure 3 is further embodiment of a detail of the invention, shown in plan view; figure 4 is a partial section of a detail of figure 3, sectioned along line III-III of figure 3. With reference to figure 1, the device consists of an automatic device for rapid connection of a chuck 1 to a chuck head 2 in bell-forming machines, where the chuck is inserted in an axial direction 5 into thermaplastic pipes 25. The chuck head is provided with a support 6 provided with a flange 4 for connecting the chuck 1, which flange 4 is provided with through holes 5 for connection of the flange 5 to the chuckhead 2, and having the task of supporting the chuck 1 projectingly and hence allowing a pipe 25 to be threaded on to the chuck 1 at the end opposite the chuckhead 2. To be able to operate on pipes of varying diameters, in a same bell-forming machine the chuck 1 can be removably constrained to the flange 4 and is provided with a central projection 3 which couples with a housing cavity 20 made on the flange 4, so that a correct centring on the chuck head 2 is achieved. Figure 1 shows how the centring projection 3 is provided with pins 9 screwed thereto, which pins 9 exhibit heads 10 and are supported by the chuck 1 such as to project posteriorly with their heads 10 arranged projectingly towards the chuck heads of the machine. The device further comprises a plate 7 located poosteriorly to the flange 4, provided with slots 8 arranged along a circumferential arc 13 and being of variable breadth, as can be seen in figure 2. The plate 7 is constrained coaxially to the support 6 such as to be at least rotatable in relation thereto and is further associable to the pins of the chuck 1 such as to enable to chuck 1 to be mounted and dismounted rapidly from the chuck head 2. As can be better seen in figures 1 and 2, the heads 10 of the pinns 9 are conformed and dimensioned such as to be able to transit freely through the holes 5 in the flange 4 and through the slots 8 in the plate 7 in a mounting position of the chuck 1 on the chuck head 2 in which the plate 7 is arranged in a first extreme rotation position in relation to the flange 4. In a second extreme position in which the plate 7 is angularly rotated with respect to the first extreme position, the heads 10 interfere geometrically and contemporaneously with the slots 8 of the plates 7, opposing a detachment of the chuck 1 from the chuck head of the machine. In a preferred embodiment, the plate 7 is ring-conformed and internally exhibits a threaded surface 21 couplable with a corresponding surface 22 of the support 6 such as to be not only rotatable but also translatable there-along. This is particularly advantageous since as the flange 4 is solid to the support 6, the translation of the plate 7 allows a striker surface 23 contiguous to the heads 10 of the pins 9 to associate with corresponding contiguous surfaces 24 of the heads 10, axially locking the chuck 1 on the head 2 contemporaneously with the rotation of the plate 7. The plate is further associated to means 11 for actuating the plate 7 rotation between the two extreme positions, which means 11 comprise a linear fluid actuator 16 (using compressed air having a first end 17 which is connected to the chuck head 2 and an opposite second end 18 connected to an arm 19 fixed to the plate 7. From figure 2 it can be seen that the slots 8 are preferably uniformly distributed along a same arc of circumference 13 of the plate 7 and exhibit a first tract 14 of a breadth corresponding to the breadth of the head 10 of the pins 9, and a second tract 15 having a breadth which corresponds to the breadth of the pns 9. To ease entrance of the plate 7 into the slots 8 as well as the flange 4 into the holes 5 the heads 10 of the pins 9 exhibit a tapered profile. A possible further embodiment of the device of the invention might be as shown in figures 3 and 4, where the plate 7 is constrained to the support 6 such as to be rotatable only with respect thereto: in any case the surface 23 of the plate 7 is slightly inclined (alpha) (about 5 degrees) with respect to the striker surface 24 of the heads 10 of the pins 9, such that during rotation of the plate 7 an adequate axial locking force is impressed on the chuck 1 through the pins 9 to oppose resistence to detachment from the chuck 1 offered by the pipe 25 and caused by radial contraction experienced by said pipe 25 during the cooling process. Constructively speaking the embodiment is realizable, as shown in figure 3, bu creating on the striker surface 23 of the plate 7 a number of inclined plane 25 situated at least at the first tract 14 of the slots 8. These planes 26 should be subjected to localized thermal treatment to grant them the hardness necessary for limiting wear thereof during repeated use of the device. Possible further embodiments of the invention can concern for example the number and arrangement of the slots 8, which might be simply two located in diametrically opposite positions on the plate 7, or three arranged at 120 degrees one to another on a cricumference 13 of the plate 7, or might even be in a greater number, and not necessarily arranged on a same circumference 13. Obviously it would be possible to change the realization of the means 11 for actuating by using incompressible fluid actuators 16 or by using equivalent mechanical systems for impressing rotation about the support on the plate between the extreme positions.

Claims: An automatic rapid-attachment chuck device for attaching axially insertable chucks (1) to machine chuck heads (2) in bell-forming machines for thermoplastic pipes, wherein the chucks (1) are removably and projectingly constrained to a fixed support(6) in the machine chuck heads (2), which support (6) is provided with a flange (4) for connecting the chuck (1), said flange (4) being provided with through holes (5) for connecting the chuck (1) to the chuck head (2), characterized in that it comprises a plate (7) affording at least two circumferential keyhole slots (8) of varying breadth and being at least rotatingly constrained to a fixed support (6) such as to be rotatably mobile in relation to the flange (4); at least two pins (9), provided with heads (10) fixed to the chuck (1) facing towards the flange (4) and with the heads (10) of the pins (9) arranged projectingly, said heads (10) being conformed such as to be able to transit freely through the holes (5) in the flange (4) and through the slots (8) in the plate in a chuck (1) mounting position on the chuck head (2) wherein the plate (7) is arranged in a first extreme rotation position with respect to the flange (4); said heads (10) interfering geometrically with all of the slots in a second extreme position in which the plate (7) is rotated in relation to the first extreme position, such as to resist a detachment of the chuck (1) from the chuck head (2) of the machine; means (11) for actuating the rotation of the plate between the first and the second extreme positions. A device as in claim 1, characterized in that the support (6) and the flange (4) are made in a single body. A device as in claim 1, characterized in that the plate (7) is slidably translatable on the support (6), meeting the heads (10) of the pins (9) in such a way as to grip the chuck (1) axially on the chuck head (2). A device as in claims 1 or 3, characterized in that the plate (7) and the support (6) exhibit complementarily threaded surfaces (21, 22) coupled together such as to render the plate (7) and the support (6) reciprocally rotatable and translatable. A device as in claims 1 or 3, characterized in that the plate (7) and the heads (10) of the pins (9) exhibit striker surfaces (23, 24) which are mutually inclined such as to lock the chuck (1) axially on the chuck head (2) during rotation of the plate (7) on the support (6). A device as in claim 1, characterized in that the slots (8) are uniformly distributed on the plate (7). A device as in claim 1, characterized in that each of the slots (8) develops along a circumference are (13) of the plate (7). A device as in claim 1, characterized in that the slot (8) exhibits a first tract (14) having a breadth corresponding to a breadth of the head (10) of the pins (9) and a second tract (15) having a breadth corresponding to a breadth of the pins (9). A device as in claim 1, characterized in that the means (11) for actuating comprise at least one linear fluid actuator (16) having a first end (17) connected to the chuck head (2) and an opposite second end (18) connected to the plate (7). A device as in claim 1, characterized in that the heads (10) of the pins (9) are tapered in order to ease an insertion of the pins (9) into the holes (5) on the flange (4) and into the slots (8) of the plate (7). A device as in claim 5, characterized in that the striker surfaces (23, 24) comprise inclined planes (26) made at least at the first tract (14) of the slots (8). A device as in claim 5, characterized in that the striker surfaces (23, 24) are made only at an edge of the slots (8). A device as in claim 6, characterized in that it comprises at least two slots (8) which are diametrically opposite to one another on the plate (7). A device as in claim 6, characterized in that it comprises three slots (8) arranged at 120 degrees one to another on a circumference (13) of the plate (7). A device, as in claim 6, characterized in that the slots (8) are arranged on more than one circumference (13) of the plate (7).

Inventors: BARATONI MAURO, BARATONI, MAURO
Applicants: SICA SPA, SICA S.P.A.
Application year: 1994
Main classification: B23Q3
IPC codes: B29C57, B23Q3